1. Field of the Invention
The present invention relates to an external electrode fluorescent lamp (EEFL) and to its fabrication method, and more particularly, to an external electrode fluorescent lamp having an external electrode disposed at both ends of the lamp with an insulation film formed at an outer surface thereof, and to its fabrication method.
2. Description of the Related Art
A cathode ray tube (CRT) is commonly employed as a display monitor, a television set, a measurement device or an information terminal, but because of its size and weight, the CRT cannot satisfy the demands for more compact and light-weight electronic products.
Thus, in line with the recent tendency that various electronic products are becoming more compact and lighter in weight, research is actively ongoing on an LCD (Liquid Crystal Display) Panel using a field optical effect, a PDP (Plasma Display Panel) using gas discharge and an ELD (Electro Luminescence Display) using a field emitting effect, in order to substitute for the CRT.
Among them, the LCD is most actively studied thanks to its advantages of having high picture quality, small average power consumption for the same screen size and a low amount of generated heat compared with the CRT. However, due to its characteristics of not emitting light, the LCD needs a light source. To accommodate this need, a reflective type LCD has been developed which uses an ambient natural light, but because of some restrictions in its use according to particular circumstances, an independent light source of the LCD itself is required. Such an independent light source is commonly referred to as a backlight, and as the light source, an EL (Electro Luminescence), an LED (Light Emitting Diode), a CCFL (Cold Cathode Fluorescent Lamp), an HCFL (Hot Cathode Fluorescent Lamp) and the like are used. Among them, especially, the CCFL which can be formed with a thin profile is in great demand.
The backlights are divided into a side light type backlight and a direct type backlight according to the location where the fluorescent lamp used as a light source is installed.
The side light type backlight is constructed such that a tubular line light source such as a fluorescent lamp is installed at the side of the liquid crystal panel and light emitted from the lamp is transmitted to the entire screen area of the liquid crystal panel by using a transparent light pipe, in a known manner.
As for the direct type backlight, its development was concentrated when the size of the LCD was increased to more than 20 inches. The direct type backlight is constructed such that a plurality of fluorescent lamps are arranged in a row at rear surface of an LCD panel and emit light to the entire surface of the LCD panel. With its high light use efficiency compared with the side light type backlight, the direct type backlight is commonly used for a large-screen LCD panel that requires high luminance.
A backlight for an LCD in accordance with the related art will now be described with reference to the accompanying drawings.
FIG. 1 is an exploded perspective view showing the direct type backlight in accordance with the related art and FIG. 2 shows a related art fluorescent lamp.
As shown in FIG. 1, the related art direct type backlight includes a plurality of fluorescent lamps 1, an outer case 3 fixing and supporting the fluorescent lamps 1 and a light scattering unit 5 disposed in front of the fluorescent lamps 1.
The light scattering unit 5 is provided to prevent the fluorescent lamps 1 themselves from visibly appearing on a display surface of the liquid crystal panel (not shown) and to make the light source have an overall uniform brightness distribution. The light scattering unit 5 can include a plurality of diffusion sheets and diffusion plates in order to increase the light scattering effect.
Also, in order to increase the use efficiency of the light, a reflection plate 7 for causing light generated from the fluorescent lamp 1 to be reflected toward a display unit of the liquid crystal panel is disposed at an inner surface of the outer case 3.
With reference to FIG. 2, the tubular type CCFL fluorescent lamps 1 are fixed in through holes formed at both sides of the outer case 3. Electrodes 2 for applying externally supplied power (not shown) are disposed at both ends at the inner side of a glass tube filled with a discharge gas, and a lead wire 9 is connected to each of the electrodes 2.
However, the related art fluorescent lamp has several disadvantages.
First, each fluorescent lamp 1 needs its own connector 11 attached to the lead wires 9 so as to permit the related art fluorescent lamp to be connected with a driving circuit.
In addition, in the related art fluorescent lamp, a hot cathode electrode or cold cathode electrode is installed at both ends of the inside of the glass tube. However, this installation process of the electrodes is quite difficult and can shorten the durability of the fluorescent lamp.